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The chisel edge comes to a point and will not walk. Bores a round, straight hole with close tolerances.
The two cutting edges are sharpened symmetrically and work in perfect unison which prolongs the life of the drill.
It can be set at any angle between 90° and 150°.
The optimal clearance angle can be set according to each drilling requirement to 7°, 9°, 11° or 14°.
One and the same drill holder copes with sizes between 3 mm (1/8") and 22 mm (7/8"). No change of chuck required.
It considerably decreases the force required on the core of the drill, i.e. the chisel edge, which reduces the heat development and permits an increased force to the cutting edges. It gives the drill a dramatic improvement in cutting performance.
The beneficial 4-facet point and the high precision sharpening – both cutting edges are sharpened to an exact equal length and symmetrically – make the drill work efficiently and the life of the drill bit is considerably prolonged.
The 4-facet geometry causes the drill to bore a straight and round hole with very close tolerances. It is crucial that both cutting edges are equal and sharpened to the same angle. This is an essential requirement so that the two edges will work in the same way and ensures that the drill will bore a straight hole, which is not larger than the drill diameter. Otherwise, the longer edge will take most of the cutting force, get overheated and more heavily worn. The result is a drill that will dull rapidly and stop working properly.
Drill bits usually have a point angle of 118° or 130°. Hardened steel and stainless steel require larger point angles. Also aluminium is best drilled with a larger point angle. When drilling plexiglass, the risk of cracks when the drill goes through the material is reduced with a larger point angle. Centering drills usually have a 90° point angle.
The choice of clearance angle is crucial to the cutting performance and duration of the drill. The optimal clearance angle depends both on the drill diameter and the material to be drilled. A harder material requires a drill with a smaller clearance angle while a softer material can have a larger angle. Standard drills have a clearance angle of 11° and a 118° point angle which work well for most drilling work.
Overheating of the steel is often not noticeable, but the consequences are that the drill will dull rapidly and may even break. Unlike conventional drill bit sharpeners, Tormek sharpens with water cooling which is gentle on the steel.
Watch the short step by step film demonstration (4:19) on the DBS-22 product page. There you will also find a film made by Alan Holtham where he tries out the jig.